DESCRIPTION To develop and extend work on patterned lipid bilayer membranes on solid supports with the ultimate goal of developing methodologies to study cell function in new and novel ways. Specifically to: Undertake an extensive characterization of the patterned solid supports and the lipid- barriers interface in the systems already developed. Develop barriers for lipid diffusion on solid supports from organic materials with the ultimate goal of gaining better control of the lipid/barrier interface and creating barriers which function in novel ways. Use the barriers to study the physical properties of two dimensional fluids, to separate and recombine charged membrane components using electrophoresis, and to attach biologically relevant molecules with controlled concentrations using electrophoresis, and to attach biologically relevant molecules with controlled concentrations using secondary photolithography or micro- mechanical methods. By creating corrals with varying concentrations of membrane associated components directly address two fundamental issues in cell function: how many receptors are required to stimulate a cellular response, and does the spatial arrangement of the receptors, e.g. clustering, play a key role? These questions are important in understanding how cells react to various stimuli and toxins and thus have important health consequences.